Effects of accelerated curing in thermoplastic particle interleaf epoxy laminates

Faster heating rates of 10 degrees C/min and higher process temperatures of 210 degrees C were applied to the commercial M21 resin system. The total process time was reduced by two-thirds while achieving the same degree-of-cure in the epoxy. Thermal analysis and hot-stage microscopy showed that the thermoplastic interleaf particles melt at around 15 degrees C above the manufacturer's recommended 180 degrees C curing temperature. A short dwell at 180 degrees C was found to prevent the thermoplastic particle from mixing with the thermoset pre-polymer before ramping to the accelerated curing temperature of 210 degrees C. Such interaction was found to decrease the glass transition temperature by 13-45 %, but increase the mode I delamination resistance by 70-105 %, respectively. The results demonstrate that accelerated curing of interleaf systems can shorten cycle time and produce a range of physical and mechanical properties from a single base material, opening the design space to new and optimised composite structures.

Automated summary

Faster heating rates and higher process temperatures can reduce the total process time while achieving the same degree-of-cure. Thermal analysis shows that thermoplastic interleaf particles melt at the recommended curing temperature. A short dwell at a lower temperature can prevent the mixing of thermoplastic particles and thermoset pre-polymer.